.png)
Texans can help prevent the spread of oak wilt - one of the deadliest tree diseases in the U.S., responsible for killing millions of trees across 76 Texas counties - by avoiding pruning or wounding oak trees from February through June.
Oak wilt is often recognized in live oaks by yellow and brown veins showing in the leaves of infected trees, known as veinal necrosis.
“Prevention is key to stopping the spread of oak wilt,” said Demian Gomez, Texas A&M Forest Service regional forest health coordinator. “Any new wound on an oak tree can be an entry point for infection including those produced by pruning, construction activities, livestock, land or cedar clearing, lawnmowers, string trimmers and storms.”
Oak wilt spreads when small insects, called sap beetles, move spores of oak wilt fungus to new trees. These beetles are very active in late winter and early spring.
Oak wilt is caused by the fungus Bretziella fagacearum, which invades the xylem, the water-conducting vessels of the trees. The tree responds by plugging the tissues, resulting in a lack of water to the leaves, slowly killing the infected tree.
All oaks are susceptible to oak wilt. Red oaks are the most susceptible and can die in as little as one month after infection. Live oaks show intermediate susceptibility, whereas white oaks are the least susceptible but not immune to infection.
Oak wilt can spread two ways: above ground by sap-feeding beetles or underground through connected roots.
Above ground spread happens when red oaks that died of the disease the previous year start producing spore mats under the bark. With a fruity smell, these mats attract the sap-feeding beetles, which can later fly to a fresh wound of other oak trees and infect them.
The second way oak wilt can spread is underground by traveling through interconnected root systems from tree to tree. Oak wilt spreads an average of 75 feet per year by the root system. This occurs primarily in live oaks and is responsible for the majority of spread and tree deaths in Central Texas.
Saving oak trees is important for the ecosystem, health, property values and community aesthetics. Loss of trees due to oak wilt can reduce property values by 15-20%.
Some cities and municipalities have oak wilt programs in place with municipal foresters dedicated to managing the disease. Texans can also contact their local Texas A&M Forest Service representative with questions about this disease. For more information on oak wilt identification and management, visit www.texasoakwilt.org.
